Wood home builders have two basic options for forming walls, ceilings, roofs, etc. The first, a long standard method, consists of using 2.times.4" studs, sills, and plates and 2.times.6" rafters, insulating between this lumber and between an inner and an outer sheathing. The insulation thickness in this case is 4" or less; and each stud, sill, and plate provides an insulation short from inner wall to outer sheathing.
More recently, prefabricated panel construction has been developed where panels of expanded polystyrene are sandwiched between fiberboard, plywood, oriented strand board, etc.
U.S. Pat. No. 4,720,948 discloses an insulated building panel that has overlapping skins. However, the panels still use 2.times.4" wood posts that join the panels and also in conduit supports, door headers, and corner posts, reducing the insulation R-values in those areas. The post construction also makes more air paths between panel sections.
U.S. Pat. No. 4,163,349 discloses a second insulated building panel that uses a considerable amount of wood as headers, sills, nailing strips, beams, plates, etc., creating a multitude of thermal "shorts". The method is silent on sealing of air leaks between panels.
Metal parts are not used as structural material in either of the above referenced patents.
It is the purpose of this invention, therefore, to develop a building construction system that: is easy to fabricate; has a high insulating "R" factor, i.e., greater than 25; is strong; uses simple available materials; has fewer parts; and is lighter than other prefabricated building components.